A belt continuously variable transmission changes groove widths of pulleys by hydraulic pressure to steplessly change a speed ratio. For such configuration, if the hydraulic pressure supplied to pulley vibrates for any cause, the speed ratio changes to cause driving force change, thus a vehicle body vibrates. The vibration of the hydraulic pressure often occurs caused by, for example, an oil pump structure, an oil passage structure, and valve characteristics.
In this respect, JP2005-121127A discloses a technique that an accumulator is coupled to an oil passage from an oil pump up to pulleys to absorb hydraulic pressure by the accumulator.